There are many types of yarn altering devices currently used in yarn production. Air operated devices include texturing devices that continuously tangle the yarn filaments to give the yarn more bulk, and entanglement devices that intermittently tangle or consolidate the filaments of multi-filament yarns so that the yarns may be more easily handled in future usages of the yarn such as in weaving and knitting. Other types of yarn altering devices that do not use air as the mechanical processing means include mechanical texturing devices, false twist devices, singeing or flame treating devices used to remove hairs, yarn brushing devices to increase the bulk by raising the hairs of a yarn, and yarn waxing devices that lubricate the yarns.
Such yarn altering devices are typically operated at very high speed and see extremely large amounts of yarn on a daily basis. Accordingly, the devices are subject to wear and breakdown. The integrity of these yarn altering devices and the other yarn handling systems in a manufacturing process are typically monitored by testing packages of yarn that have been processed through the production equipment. If there is a problem with the yarn on a package, the test personnel know that there is a problem with the equipment somewhere in the manufacturing process. However, it is then difficult to pinpoint the specific problem without being able to measure the performance of any yarn altering device within the production system.
When any yarn altering device in a production process is replaced, it of course may be the source of a problem. However, once the device is placed in production, there is really no means of easily pinpointing that that device is the source of a problem until the yarn produced is tested at a later time, and by that time large quantities of defective yarn may have been made.